Field of the Invention
The present invention relates to fastener tools, and more particularly to concrete nailers.
Description of the Related Art
Concrete nailers are quite different from conventional nailers designed simply for nailing wood and metal together. As may be imagined, driving a nail into concrete requires much higher energy and produces greater impacts than driving nails into metal or wood. Driving a nail into concrete requires that the systems of a concrete nailer be made much more robustly, and that those systems be especially configured to deal with the particular challenges presented to a concrete nailer on a job site, which are not encountered by conventional nailers. Also, it has now become imperative that, for maximum flexibility, concrete nailers use magazines which can accommodate nails ranging in length from ½ inch to at least 2¼ inches. Furthermore, it is important that when driving nails into a concrete work surface, the nail be oriented as close to 90° as possible to the concrete, so that the concrete does not chip, crack or break away, as is likely to occur if the nail is impacted at an angle relative to the concrete. These requirements present a significant test for a concrete nailer when the concrete nailer is required to nail a deep track to concrete.
“Tracks” are U-shaped steel channels for holding everything from electrical conduits and piping, to partitions, other structural members, and the like. Tracks have become ubiquitous on a job site, and consequently it would be very desirable to provide a concrete nailer capable of quickly and easily nailing tracks to concrete work surfaces. However, the vast range of sizes of tracks used in construction has presented a challenge to the operator, who will frequently encounter on the same job, tracks having widths ranging from 30 mm to 100 mm, and depths ranging from 20 mm to 70 mm. On the one hand, if the operator encounters a track at the wide and shallow ends of the range (e.g. 100 mm wide×20 mm deep), the operator can position the concrete nailer so that the drive axis of the nail is maintained at 90° relative to the channel and concrete. However, as the track gets narrower and deeper, the ability of the operator to drive a nail perpendicularly into the track becomes increasingly difficult. The operator must now skew the concrete nailer so that the nail magazine, which is often mounted on a lower surface of the nailer housing, clears a vertical wall of the track. But then, as the track width approaches 30 mm and the depth approaches 70 mm (a “deep track”), it becomes almost impossible for an operator using a conventional concrete nailer having a magazine large enough to accommodate both short and long nails to drive a nail perpendicularly to the track. The magazine of such a concrete nailer blocks an operator from having sufficient “reach” into the track so that the nailer contact trip cannot be fully depressed against the base of the track, thereby preventing the nailer from being fired. To accommodate all of the sizes of tracks likely to be available on a job site, the reach should be 60-70 mm, and preferably 70 mm.
Nail lengths further complicate the concrete nailer arena. Short nails are commonly used to nail track to concrete. There are conventional concrete nailers that use magazines which only accommodate short nails. Short nails enable magazines to be made with relatively short heights, thereby creating sufficient reach for the operator to drive the nails perpendicularly to the base of the track and into the concrete. Conversely, magazines that are tall enough to accommodate long nails will also block conventional concrete nailers from satisfactorily nailing into track. “Long nails”, in this context, are nails which are long enough to nail 2×4's to concrete, which means they must be at least 2¼ inches long. Nailing 2×4's to concrete is another critical job that contractors need to perform. However, switching between a short fastener magazine and a long fastener magazine results in a significant cost, because the contractor must maintain at least two nailers on the job site, one loaded with short nails and another loaded with long nails; or the contractor must provide the nailer with at least two different magazines, one containing short nails and the other containing long nails. However, switching out various magazines takes time, which increases cost.
An unsuccessful attempt has been made to solve both problems. A concrete nailer using a magazine that accommodates both short and long nails was introduced with an unusually long drive track and contact trip subassembly to artificially create enough reach for the nailer to drive nails into many sizes of tracks, as well as to accommodate 2¼ inch nails. However, generating an unusually long drive track and contact trip subassembly also requires that the rest of the nailer be made taller. The result is a concrete nailer which is heavier, more unwieldy and less able to fit into tight spaces than the other concrete nailers. (The height of the conventional nailer is 18½ inches.) Moreover, making the tool larger inevitably adds cost. However, the maximum reach attained with the conventional concrete nailer is only 50 mm, and consequently it has much less flexibility to accommodate the sizes of tracks likely to be found on the construction site then one having a reach of 70 mm.
The dilemma faced by conventional concrete nailers is shown in FIGS. 1-3, which illustrate how a first conventional concrete nailer 100, 100′ is unable to accommodate both short and long nails 40, 42 and still drive them perpendicularly into a complete range of tracks 44 likely to be encountered on the job site. FIG. 1 shows that a first conventional concrete nailer 100, having a housing 102 to which is connected a magazine 104, is able to depress its contact trip 106 against the base 46 of the track 44, because the height H1 of the magazine need only accommodate short nails 40. However, as shown in FIGS. 2 and 3, when concrete nailer 100′ uses a magazine 104′ that has a height H2 for accommodating long nails 42 as well short nails 40, full actuation of the contact trip 106 becomes geometrically impossible when the drive axis 22 is oriented at an angle A of 90° to the base 46 of track 44. Thus, concrete nailer 100′ is blocked by the conventional magazine 104′ so that the contact trip 106 is held above the bottom 46 of track 44 by a distance G, and consequently is unable to fire.
Referring now to FIGS. 4, 5 and 6, a second conventional concrete nailer 200 that unsuccessfully attempts to overcome such deficiencies includes a housing 202 and a magazine 204 configured to accommodate both short and long nails 40, 42. The magazine 204 is disposed at an unusually large distance above a work surface. The purpose was to artificially create enough reach R so that the second conventional concrete nailer 200 can handle many sizes of track 44 likely to be found on a job site. However, this additional flexibility comes at a price. In order to elevate magazine 204 at such a distance above the track 44, it is also necessary concomitantly to lengthen the contact trip 206 and drive system 218. When such components as the contact trip 206 and drive system 218 are elongated, or made taller, the housing 202 and all of the other components disposed therein must also be made taller, as shown in FIGS. 5 and 6. The resulting overall height H2 above the work surface 34 of the second concrete nailer 200 must now be 18½ inches.
Thus, it can be seen that in the demanding field of concrete nailers, the ranges of track dimensions, the length of reach, and the size ranges of nails used in concrete nailer magazines are in fact critical parameters.
Consequently there has been generated a long-felt need for a concrete nailer that accommodates both short and long nails, that drives nails perpendicularly into the entire range of tracks likely to be available on a construction site, and that also has the flexibility to nail 2×4's to concrete.